Modern silviculture often requires the planting of large numbers of genetically identical plants that have been selected to have advantageous properties. Production of new plants by sexual reproduction, which yields botanic seeds, is usually not feasible. Asexual propagation, via the culturing of somatic or zygotic embryos, has been shown for some species to yield large numbers of genetically identical embryos, each having the capacity to develop into a normal plant.
Somatic cloning is the process of creating genetically identical plants from plant tissue other than male and female gametes. In one approach to somatic cloning, plant tissue is cultured in an initiation medium that includes hormones, such as auxins and/or cytokinins, to initiate formation of embryogenic tissue, such as an embryogenic suspensor mass, that is capable of developing into somatic embryos. An embryogenic suspensor mass, or ESM, has the appearance of a whitish translucent mucilaginous mass and contains a plurality of early stage embryogenic tissue. The embryogenic tissue is further cultured in a multiplication medium that promotes multiplication and mass production of the embryogenic tissue. The embryogenic tissue is then cultured in a development medium that promotes development and maturation of cotyledonary somatic embryos that can, for example, subsequently be placed on germination medium to produce germinants, which in turn can be transferred to soil for further growth. Alternatively, the cotyledonary somatic embryos can be placed within manufactured seeds and sown in soil where they germinate to yield seedlings. Manufactured seeds are described, for example, in U.S. Pat. Nos. 5,564,224; 5,687,504; 5,701,699; and 6,119,395.
The somatic embryogenesis process is laborious and inefficient. For example, one of the more labor intensive steps in the embryogenesis process is the harvesting of individual plant germinants from gelled germination medium by a skilled technician. The harvesting process is a tedious job that is time consuming and causes ergonomic stress to workers. Further, it poses a major production bottleneck when the ultimate desired output can be in the thousands of plants.
There is a continuing need to improve the efficiency of harvesting plant germinants in order to reduce labor and technician fatigue, reduce the risk of worker injury, and increase the production rate to achieve commercial scale.
The present disclosure describes methods of separating plant germinants en masse from gelled germination medium.